Show Posts
Postings on webcam blog:
broken egg retrieved
Published 19 September, 2014 | By Cilla Kinross
I went up to collect the broken egg today and caused some disturbance, so the remaining eggs were uncovered for about 25 minutes. Will get back to you with results on egg thickness as soon as possible.
egg shell thickness
Published 19 September, 2014 | By Cilla Kinross
I took 20 measurements of the egg using calipers on the broken edges to try and avoid the curve and the average was 0.31 mm (standard deviation of 0.02).
According to USGS Biological and Ecotoxicological Characteristics of Terrestrial Vertebrate Species Residing in Estuaries ‘Peregrine Falcon’ pre DDT shell thickness is generally around 0. 35-36 and post DDT it dropped by 10-22 % to 0.27-0.29.
So our Swift’s eggs would seem to be quite thin. This may reflect the high percentage of starlings and pigeons in their diet as contaminants tend to accumulate particularly strongly in these species.
I’ll see what it costs to have the eggshell (which is now in pieces) tested for contaminants.
Comments are welcome.
broken egg retrieved
Published 19 September, 2014 | By Cilla Kinross
I went up to collect the broken egg today and caused some disturbance, so the remaining eggs were uncovered for about 25 minutes. Will get back to you with results on egg thickness as soon as possible.
egg shell thickness
Published 19 September, 2014 | By Cilla Kinross
I took 20 measurements of the egg using calipers on the broken edges to try and avoid the curve and the average was 0.31 mm (standard deviation of 0.02).
According to USGS Biological and Ecotoxicological Characteristics of Terrestrial Vertebrate Species Residing in Estuaries ‘Peregrine Falcon’ pre DDT shell thickness is generally around 0. 35-36 and post DDT it dropped by 10-22 % to 0.27-0.29.
So our Swift’s eggs would seem to be quite thin. This may reflect the high percentage of starlings and pigeons in their diet as contaminants tend to accumulate particularly strongly in these species.
I’ll see what it costs to have the eggshell (which is now in pieces) tested for contaminants.
Comments are welcome.
Seems strange they did fine with their eggs previous to last year, could they be using DDT again in this part of Australia? Or is it just the age of Swift? Hope it's not too expensive to test for contaminants, because this would definitely answer the question! Praying the remaining 2 eggs have a bit thicker shell!
